Patent Literature 1 describes a hybrid vehicle including, as shown in FIG. 20, a flywheel driving generator 113 which rotationally drives a flywheel 112 or which generates electricity using the flywheel 112, a drive shaft driving generator 116 which rotationally drives a drive shaft DS or which generates electricity by retarding the motion of the drive shaft DS, a battery 115 which stores electric energy for starting, a generating device 111 (preferably a fuel cell) which generates driving electricity, and a power controller 117 which controls the flywheel driving generator 113 and the drive shaft driving generator 116. When vehicle driving electric power is larger than a generated electricity output capacity of the generating device 111, the power controller 117 controls so that electricity is generated by the flywheel driving generator 113. In addition, when the vehicle driving electric power is smaller than the generated electricity output capacity and when the brakes are applied to slow or stop the vehicle, the power controller 117 controls so that surplus electric power and electric power generated during braking are stored in the flywheel 112 as energy.
Patent Literature 2 describes a fuel cell hybrid electric vehicle which is equipped with a fuel cell 211 and a flywheel 212 as shown in FIG. 21, including, for storing braking energy of the vehicle, a main transmission 214 and a main clutch 213 which are provided between an electric motor 216 and the flywheel 212, a battery 215 which stores electric energy for starting the fuel cell electric vehicle, and a flywheel controller 217 which controls them, wherein the flywheel controller 217 controls the flywheel 212, the main transmission 214 and the main clutch 213 so that electric energy from the fuel cell 211 and the battery 215 is converted into mechanical energy via the electric motor 216, transmits the mechanical energy to a drive shaft DS and stores surplus mechanical energy. Reference numeral 222 denotes a sub clutch, and reference numeral 223 denotes a sub transmission, reference numeral 224 denoting a differential gear.